This disclosure relates to transformer paper and other non-conductive transformer components. Electrical devices and components often employ paper insulation to surround and electrically insulate an electrical conductor. One such electrical device is a transformer that has at least two electric circuits that share a common magnetic flux, so that a voltage in one circuit magnetically induces a voltage in the other circuit. In addition, a magnetic path can be provided by an iron core. The electric circuits and the core can be immersed in a dielectric fluid in an enclosure. These dielectric fluids are also referred to as transformer oils and transformers containing them are referred to as oil-filled transformers. The conductors that make up the electric circuits are separated and electrically insulated from each other and from other components, such as the core and the enclosure, by paper insulation.
Non-conductive components in oil-filled transformers (spacers, oil ducts, paper (both porous and non-porous, as well as creped), board, plastic bolts, ropes, etc.) have often been made from cellulosic and other hydrophilic materials (i.e. paper, pressboard, wood, cotton, nylon, etc.). These materials have disadvantages in that they degrade when exposed to high temperatures and introduce water into the oil-filled transformer as a by-product of their decomposition. Water contamination of the oil-filled transformer is highly undesirable since it degrades the performance of the transformer through electrical discharge activity and lossiness, causes further degradation of non-conductive components, and, ultimately, electrical failure of the transformer.
In addition to their negative effect on service life, cellulosic and other hydrophilic materials force delays in the production cycle time for oil-filled transformers. Due to the tendency of cellulosic and other hydrophilic materials to retain moisture, these non-conductive transformer components undergo a prolonged drying process before assembly into an oil-filled transformer. It has also been observed that the drying process can result in embrittlement of these components, which can also cause reduced service life of the transformer.
U.S. Pat. No. 6,980,076 relates to improved cellulosic insulation papers which contain synthetic reinforcing fibers intended to extend the usefulness of cellulosic papers as they degrade during their service life by providing a reinforcing web. However, this improved cellulosic paper still releases water as it ages causing water degradation of oil-filled transformers and the art still has an unmet need for improved electrical insulation paper.
It would therefore be desirable to replace the cellulosic and hydrophilic non-conductive structures with comparable structures that do not share this disadvantage. Doing so could afford a transformer that would run at higher temperatures, higher energy density, and for longer life—all of which will be necessary for updating the electric grid and mitigating the impact of electric vehicles on distribution and power transformers. Furthermore, such transformers could be faster and easier to manufacture and result in faster, lower cost repairs, as well.